See seek on how to rewind a file handle.

Also note that <READ1>.<READ2> doesn't check for the definedness of both the return values.

Moreover, chomping a line to append \n to it in the next line is useless. Chomping a file name after having used it makes no sense, chomp it before you use it, and use 3-arg open (which doesn't remove whitespace from its 3rd argument).

Don't rewind the second file after having rewound the first one, otherwise you'll get an infinite loop.

#!/usr/bin/perl
use warnings;
use strict;


chomp( my $input1 = <> );
chomp( my $input2 = <> );
my $output = 'output.txt';


open my $READ1, '<', $input1 or die "Cannot open $input1: $!.\n";
open my $READ2, '<', $input2 or die "Cannot open $input2: $!.\n";
open my $WRITE, '>', $output or die "Cannot open $output: $!.\n";

my $rewound = 0;
until ($rewound == 1 && eof $READ2
    || $rewound == 2 && eof $READ1
   ) {
    my $line = <$READ1> . <$READ2>;
    if (eof $READ1 && $rewound != 2) {
        seek $READ1, 0, 0;
        $rewound = 1;
    } elsif (eof $READ2 && $rewound != 1) {
        seek $READ2, 0, 0;
        $rewound = 2;
    }
    print {$WRITE} $line;
}
close $WRITE;
print "done\n";

[download]
($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

In reply to Re: writing two files (different in length) to one output by choroba
in thread writing two files (different in length) to one output by ic23oluk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.